The role of distinct metal cocatalysts in tuning β-ZrNBr for diverse photocatalytic applications

Abstract

The deposition of suitable metal cocatalysts onto semiconductor surfaces is a highly effective strategy for enhancing photocatalytic performance. However, the underlying microscopic mechanisms that dictate the optimal choice of metal for a specific semiconductor remain insufficiently understood. This work aims to establish a structure-property relationship for metal-decorated β-ZrNBr, focusing on the fundamental question of why certain metals excel as cocatalysts for particular photocatalytic reactions. We systematically constructed and analyzed M/ZrNBr (M = Rh, Pd, Pt, Au) heterostructures with controlled metal layer thickness (1-3 layers) to probe their structural stability, electronic structures, and performances in the photocatalytic hydrogen evolution reaction (HER) and the two-electron water oxidation for hydrogen peroxide (H 2 O 2 ) production. All heterostructures demonstrate robust structural and thermal stability. Electronic structure analysis reveals that Rh, Pd, and Pt induce metallization of the ZrNBr surface, whereas Au/ZrNBr preserves its semiconducting character. For the HER, multi-layer Rh and Pd systems exhibit nearoptimal hydrogen adsorption free energies (|ΔG H | ≈ 0), suggesting their potential as alternatives to Pt. In contrast, for the two-electron water oxidation reaction, Audecorated ZrNBr with thicker metal layers show a significantly lower theoretical overpotential (by 0.8-1.2 V) than other systems, identifying it as the thermodynamically most favorable catalyst for H 2 O 2 production. Our theoretical calculations successfully validate the experimental observations. This study provides atomic-scale insights into the role of metal identity and thickness in tuning catalytic performance, offering a solid theoretical foundation for designing high-performance β-ZrNBr-based photocatalytic systems.